Effect of Wire Grid Covering Aperture on the Shielding Performance of Metal Rectangular Enclosure

Based on the method of moment (MOM), a new method is developed to evaluate the electromagnetic shielding effectiveness of the rectangular metal enclosure with aperture covered with wire grid. The wire grid is modeled as thin wire, and the currents on the wire segments, which are taken as unknowns, are modeled by triangular basic functions. In order to expand the unknown electric currents on the surface of the cavity, Rao-Wilton-Glisson (RWG) basic functions are used on the surface patches to model the concerned objects. In terms of the continuity of the tangential electric fields on the surface of conductive plane and thin wire, a set of equations can be established. From the equations set, the currents on the surface patches and wire grids can be obtained. The accurate shielding effectiveness of the rectangular enclosure of metal structure with apertures covered with wire grid can be determined. By comparing the calculation with measurement results, the method is validated. Finally, the shielding performance of a protection cell in a practical substation is analyzed as an application.